// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_BASE_NETWORK_CHANGE_NOTIFIER_WIN_H_
#define NET_BASE_NETWORK_CHANGE_NOTIFIER_WIN_H_

#include <windows.h>

#include <memory>

#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "base/threading/non_thread_safe.h"
#include "base/timer/timer.h"
#include "base/win/object_watcher.h"
#include "net/base/net_export.h"
#include "net/base/network_change_notifier.h"

namespace net {

// NetworkChangeNotifierWin inherits from NonThreadSafe, as all its internal
// notification code must be called on the thread it is created and destroyed
// on.  All the NetworkChangeNotifier methods it implements are threadsafe.
class NET_EXPORT_PRIVATE NetworkChangeNotifierWin
    : public NetworkChangeNotifier,
      public base::win::ObjectWatcher::Delegate,
      NON_EXPORTED_BASE(public base::NonThreadSafe) {
public:
    NetworkChangeNotifierWin();

    // Begins listening for a single subsequent address change.  If it fails to
    // start watching, it retries on a timer.  Must be called only once, on the
    // thread |this| was created on.  This cannot be called in the constructor, as
    // WatchForAddressChangeInternal is mocked out in unit tests.
    // TODO(mmenke): Consider making this function a part of the
    //               NetworkChangeNotifier interface, so other subclasses can be
    //               unit tested in similar fashion, as needed.
    void WatchForAddressChange();

protected:
    ~NetworkChangeNotifierWin() override;

    // For unit tests only.
    bool is_watching() { return is_watching_; }
    void set_is_watching(bool is_watching) { is_watching_ = is_watching; }
    int sequential_failures() { return sequential_failures_; }

private:
    class DnsConfigServiceThread;
    friend class NetworkChangeNotifierWinTest;

    // NetworkChangeNotifier methods:
    ConnectionType GetCurrentConnectionType() const override;

    // ObjectWatcher::Delegate methods:
    // Must only be called on the thread |this| was created on.
    void OnObjectSignaled(HANDLE object) override;

    // Does the actual work to determine the current connection type.
    // It is not thread safe, see crbug.com/324913.
    virtual ConnectionType RecomputeCurrentConnectionType() const;

    void SetCurrentConnectionType(ConnectionType connection_type);

    // Notifies IP address change observers of a change immediately, and notifies
    // network state change observers on a delay.  Must only be called on the
    // thread |this| was created on.
    void NotifyObservers();

    // Forwards connection type notifications to parent class.
    void NotifyParentOfConnectionTypeChange();

    // Tries to start listening for a single subsequent address change.  Returns
    // false on failure.  The caller is responsible for updating |is_watching_|.
    // Virtual for unit tests.  Must only be called on the thread |this| was
    // created on.
    virtual bool WatchForAddressChangeInternal();

    static NetworkChangeCalculatorParams NetworkChangeCalculatorParamsWin();

    // All member variables may only be accessed on the thread |this| was created
    // on.

    // False when not currently watching for network change events.  This only
    // happens on initialization and when WatchForAddressChangeInternal fails and
    // there is a pending task to try again.  Needed for safe cleanup.
    bool is_watching_;

    base::win::ObjectWatcher addr_watcher_;
    OVERLAPPED addr_overlapped_;

    base::OneShotTimer timer_;

    // Number of times WatchForAddressChange has failed in a row.
    int sequential_failures_;

    // Thread on which we can run DnsConfigService.
    std::unique_ptr<DnsConfigServiceThread> dns_config_service_thread_;

    mutable base::Lock last_computed_connection_type_lock_;
    ConnectionType last_computed_connection_type_;

    // Result of IsOffline() when NotifyObserversOfConnectionTypeChange()
    // was last called.
    bool last_announced_offline_;
    // Number of times polled to check if still offline.
    int offline_polls_;

    // Used for calling WatchForAddressChange again on failure.
    base::WeakPtrFactory<NetworkChangeNotifierWin> weak_factory_;

    DISALLOW_COPY_AND_ASSIGN(NetworkChangeNotifierWin);
};

} // namespace net

#endif // NET_BASE_NETWORK_CHANGE_NOTIFIER_WIN_H_
